Energy of a Slingshot: David and Goliath

first: click "slingshot pullback" (▶) and wait until it finishes

next: click "shoot" (▶) (click again to repeat)

adjust strength of elastic:

adjust mass (and size) of stone:

David defeated Goliath by striking him on the forehead with a stone from a slingshot. How did David do it? The key quantities are the energy and speed of the stone. The greater the energy, the greater the damage to the target (Goliath's head), and the greater the speed, the less likely Goliath will be able to dodge the stone. This Demonstration shows energy being transferred to the elastic bands of the slingshot and then to the stone as energy of motion (kinetic energy). You can vary the mass of the stone and the strength of the bands.

If you were David, how would you maximize the kinetic energy and speed of the stone? Would you use a heavy or a light stone, and strong or weak elastic bands? Investigate to find out!

This Demonstration is intended only to illustrate the principle of conservation of energy. Polymers with requisite properties and other technological advances in slingshots were not available to David at the time (fortunately for Goliath?).